3-D Woven Preform Joint Testing to Support the D8 Double-Bubble Composite Fuselage Design

Abstract

The D8 double-bubble aircraft features a wide fuselage to enable operational improvements from a twin-aisle seating arrangement as well as fuel efficiency improvements due to increased fuselage aerodynamic lift, a more favorable fuselage pitching moment, and in some variants the installation of rear fuselage mounted boundary layer ingesting turbofan engines. The wide fuselage outer mold line consists of a vertically joined dual-lobe fuselage cross-section. The double-bubble configuration introduces unique features of the primary airframe structure when compared with classical tube or horizontally joined multi-lobe fuselage configurations as the vertical joint cannot take advantage of a floor at the lobe intersection. The structural “Yâ€- joint of the double-bubble fuselage is composed of the co-cured fuselage skin and 3-dimensional woven composite preform and a keel. In this paper, mechanical testing of the 3-D woven composite preform is setup to support the development of the D8 double-bubble fuselage “Yâ€-joint. The challenges of a wide-body fuselage, the structural solution used on the D8 concept, and the testing involved to validate the effectiveness of the solution in a commercial application are presented.